Process for the production of metallic screens



July 18, 1939. E. o. NORRIS PROCESS FOR THE PRODUCTION OF METALLICSCREENS Original Filed Dec. 6, 1954 3 Sheets-Sheet 1 IN VEN TOR WWAA'W ATTORNEYS July 18, 1939. NORRIS 2,166,367

PROCESS FOR THE PRODUCTION OF METALLIC SCREENS Original Filed Dec. 6,1934 3 Sheets-Sheet 2 INVENTOR WW M ATTORNEYS July 18, 1939.

E. o. NORRIS 2,166,367

PROCESS FOR THE PRODUCTION OF METALLIC SCREENS Original Filed Dec. 6,1934 5 Sheets-Sheet 3 INVENTOR WQ/dv QM,

A TTORJVE VJ tented July 18, 1939 NM -F CE Iron m raonoorron or a martime scanners 'Edward OmarNorrIa-We ItpoI-t, Coma, auig nor to. Edward0. Norris, Ina,

. peorporation of New York strengthen a, 1934, Serial No. maze New York;N. Y.,

* a BoueIedDecember 14,103: 150mm (01. 204-4) This invention relates tometallic screens and to. the formation thereof; and to correlatedimprovementsand discoveries appertaining thereto. An object of theinvention is to provide an improved metallic screen. I

More specifically it is an object of the invention to' provide metallicscreens having advantageous properties when compared to wire mesh orPunched-screens. f j

Another object is the provision of particularly fine-mesh screens ofadvantageous character.

Another object is to provide a matrix from which improved screens may beeffectively formed. 7

Another object isthe provision of an improved process for the provisionof a matrix for screen formation.

Other objectsof the invention will in part be obvious and will in partappear hereinafter,

The invention accordingly comprises the several steps and the relationof one or more of such steps with respect to each of the others, and thearticle possessing the features, properties and the relation ofelements, which are exemplified in the following detailed disclosure,and the scope of the application of which will be indicated in theclaims. r

For a fuller understanding of the nature and objects of the inventionreference should be had to the following detailed description taken inconthe accompanying drawings, in

in the development of said device;

- Fig. 10 is a. similar view of a screen'formed on g rlid gartiallyremovedfrom the matrix shown in Figs, llthrough 17 are-similar views ofa modiflcation of the device shown in Fig.- 1 and shown in successivesteps in the development thereof; I

Figs. 18 and 19 are similar views of a modification of the matrix'show'nin Fig.1? and showing successive steps in the development of saidmodification; I i r i Figs. 20 and 21 are sectional views in elevationof the matrix shown in Fig. 19 as a screen is being formedthereon;

, Fig. 22 is' a perspectivview of a'screen' partially removed from thematrix shown in Fig. 19;

Fig. 23 is similar to Fig. 21 and shows a modification of the step shownin Fig. 21;

Fig, 24 is a plan view of a screen made by a method including the stepshown in Fig. 23; and

Fig. 25 is across section in elevation of the I screen shown in Fig. 24taken along the line 2%". a

The use of mesh screens, especially for fine work, is subject to manydisadvantages, among which is the tendency for particles just largeloenough so that they do not pass through thescreen to lodge above theopenings in the screen. There are, moreover, practical limitations tothe fineness of mesh which can be produced and used commercially. Forthis reason non-metallic screens arere- 1 lied on for many purposes forwhich metallic screens would otherwise be better adapted, or in whichmetallic screens would have a much longer life, An example of this isthe use of bolting cloth in the sifting of flour. For relatively coarsework 20 mesh screens are still used for many purposes in connection withwhich screens of the character contemplated by the invention would havedefinite advantages. There are also many instances wherein a flat screenhaving a large percentage of 25 There is furthermore a considerable needfor 80 metallic stencils wherein the openings" instead of being entirelycut away are composed of a metallic portion with fine, substantiallyuniform, holes throughout the extent of the openings.

In screen printing processes atthe present time silk screens areutilized because of the lack of any available satisfactory metallicscreen. The use of a silk screen, however, involves a careful andtime-consuming operation of blocking out all portions which it is notdesired to print, and also 40 issubiect to difllculties because of thelack of strength of silk screens.

With a view to overcoming the foregoing and other diflieulties, thepresent invention is directed to the provision of a screen having asmooth up- 4-5 per surface with a large number of closely-spaced holestherethrough, and of a stencil having, besides solid portions, non-solidportions with a smooth upper surface and with a large number ofclosely-spaced holes therethrough. Inacproduced electrolytically,preferably metal de- 2 amass? 8ordinarymetallicsheetssuchasrolledordrawn sheets. This may be due to auniformity of thickness throughout the sheet, or uniformity of theinternal structure of the sheet, or to a uniformityintheresistancetoanetchingactionbutatall l0eventsvariationsinthetimeinwhichthedifierent holes etch through ismarkedly reduced. It is tobeobservedinthisconnectionthatwberea pluralityof holesis being etched from a sheet in an etching bath, and where oneof these holes llisetchedthroughbeforetheothentheetching chemical exertsa sidewise etching on the first hole so as to make it larger than theother holes. It is found possible to produce larger metallic sheets ofrigorously uniform thinness by electrodeposition than by other methods.

' By way of example there is exemplified below one specific type ofprocedure which may be utilined in the formation of a matrix for theproduction of screens of the character above indicated.

' A thin sheet I! of metal such as copper is thoroughly cleaned andfastened to a fiat surface such as a glass plate, as with adhesive tape.The thickness of the sheet may be about five-thousandth! of an inch(0.005"). The sheet should have a I) uniform thickness, and for thispurpose electrolytic metal, such as electrolytic copper, is desirable.In order to provide a sheet having a smooth, uncrinkled surface, thesheet may be formed by plating copper on a sheet of commercial electro-0l lytic copper two-thousandths of an inch (0.002") thick.

An etch-resistant design is applied to a face of the sheet in anysuitable fashion. The following is one method of doing so: The sheet ispolished a and coated with a sensitised glue solution of any suitablenature. One such solution which may be utilised may be formed by mixing'1 ounces (avoirdupois) of clarified glue with 16 fluid ounces of water,6 drama of ammonium bfchromate, the al- 5 bumen of 8 eggs, and 8 dropsof ammonia. After application, the glue solution is drained from thesheet, and the sheet dried over a source of heat. It is thereupon put ina vacuum frame under a fiat-screen negative embodying opaque dots sep- Qarated by interconnected clear lines, and exposed to are light orsunlight'for five or ten minutes. It is then immersed in a watersolution of methyl violet and washed out in clear water. After drying,the screen print may be examined under a a; magnifying glass for faults,and if any are found, these may be corrected by handwork. The print isthereupon heated over a gas fiame until the print is burned to a darkbrown. The design superimposed upon the metal sheet is, in the casedescribed, a network of intersecting lines ii of developed glue (seeFig. l). I

After the formation of a screen design on the sheet by the foregoing orother suitable method, or at a previous time, the sheet is coated on theas back with a protective material it, for instance.

shellac, and dried. In order to enable the operator to assure himselfthat the shellac completely covers the sheet, tinted shellac may beused. The printed and protected sheet is immersed in an 70 etchingsolution, such for instance as ferric chloride, to form depressions IIin sheet ll (see Fig. 2) between the lines of the print throughout thesheet. After etching to a suitable depth, depending upon the height andphysical properties of 15 certain protuberances described below, thesheet iswaahedandthoroughlycieanedmsbyamix ture of common salt andvinegar. Aftcrthesheet isdriedtheetchedsideiscovered withanonconducting,semi-liquid material ll, which willadheretotheetchedsurfaceandwhichwillnot I .be attacked by a subsequentetching solution. An

acid-resistant paint, for example, that known under the trade name ofCe-Oo Super-Chemical Resistant Finish, may be used. The term"nonconducting material, used in this connection 1. throughout thespecification .and claims, is intendai to include not only materials ofhigh electrical resistivity but also those materials, even of lowresistivity, onto which it is difficult to electroplate. Excess materialis removed with a squeegee is so as to leave the surface of thedepressions covered with material as in Pig. 3. The covered surface isthen immediately dusted over with a finelydivided. granular conductivematerial II, such as copper powder, and allowed to dry for five or six Uhours (see Fig. 4)

The intersecting cross ridges ll of developed glue are removed, forexample, by sandpapering, and the remainder of the surface scrubbed toremove all metal powder which does not actually I adhere to thenon-conductive materiaHsee Pig. 5). The surface thus formed is thenplated with metallic material ll, such as copper, to a depth of, forinstance, about four-thousandths (0.004) or five-thousandths (0.005) ofan inch (see Fig. I 6). The copper powder or other granular materialassists in holding the deposited material firmly on the non-conductivematerial. Thereafter the shellac I! on the unetched side of the plate isremoved with alcohol, and the plated side coated II with shellac II, orother protective material, which is allowed to dry (see Fig. 'l). Theplate is then immersed in an etching bath which eats into the originalmetal to form a matrix having protuberances of non-conductive materialand intercona nected valleys where the metallic material is exposed asshown in Fig. 8. Fig. 9 is a view of the matrix shown in Fig. 8, butviewed from below.

In order to provide an effective matrix, the protuberances preferablyshould not be substantially as less than one-thousandth (0.001) of aninch in height.

Any equivalent process may be substituted for the etching bath mentionedabove. For example,

. the original matrix may be removed'by abrasion w or sand blasting orby electro-corrosion in a conducting bath. The term etching in thespecification and claims is accordingly not to be limited to the actionof a solvent upon a soluble solid.

Instead of the print of intersecting lines shown as on the metallicsheet in Fig. l, a print of raised, spaced elements may be applied as adesign to a suitable surface and a casting made therefrom of somelow-meltlng-point material such as wax.

In the interstices or depressions of this casting a so non-conductingmaterialis inserted preferably as aliquid. A conducting powder issprinkled over one face of the casting and the spaced quantities ofnon-conducting material, which latter is permitted to harden. A layer ofthe metal is then 06 electroplated upon the conducting powder and thewax melted away leaving a matrix similar to that shown in Fig. 0, exceptfor the coat of shellac In certain instances there is a tendency for a70 screen plated on such a matrix to stick occasionally in spots and toleave portions of its body on the matrix when stripped therefrom. Inorder to permit these portions to be readily removed by etching, thevalleys in the matrix may be plated 7i amass-r with an etch-resistantcoating of suitable materi such as platinum, which may be applied byplating a thin layer over these portions. By way of example, there aredescribed below several processes whereby a screen may be formedelectrolytically on a matrix having protuberances which presentanon-conductive surface such as is described above.

There may be provided on the matrix a film l8 ofmaterial which willmaintain electro-deposlted material as an independent layer andfacilitate stripping of electro-deposited material from the matrix. Sucha film may be formed on the matrix itself as by oxidation or othersuitable process, or may be provided by a material supplied thereto. Atall events the film should be thin enough and of such character as notto interfere materially with the'electro-deposition of material on themetallic portions of the matrix. One procedure which may be utilized isto flow a thin mixture of beeswax and naphtha over it and allow it todry. The matrix is then placed as an anode in a suitable platingsolution, such, for instance, as a copper bath, and metalelectro-deposited on the metallic valleys in the matrix, there being, ifdesired, the stripping facilitating film described above, between themetal forming the valleys of the matrix and the lastmentioned metal,which last-mentioned electrodeposited metal is to comprise the desiredscreen. The latter may be built up to any desired thickness and thedeposit It! thus formed stripped from the matrix as shown in Fig. 10. Ifthe electro-cleposition is stopped at a point where the deposit is wellbelow the tops of the protuberances there is provided a thin screen ofsatisfactory quality. When a thicker screen is desired the depositionmay be carried to a point where it almost reaches the top of theprotuberances. The deposited material is then stripped off and the topand bottom surfaces thereof run on a roller which applies anacid-resistant type of stencilling paste, e. g., du Pont's blackstencilling paste, or of printing ink thereto. The sheet which has beenstripped off is then immersed in an etching bath. The ink acts topreventetching of the upper surfaces, but the contiguous projections at the topof the deposit are quickly cut away so that the holes are of the desiredshape. Another procedure which may be utilized is to carry the platingto a point where the deposited metal entirely covers the protuberances.This will result in upward bulges on the lines between theprotuberances, with thin portions over the protuberances. Afterstripping, the lower points on the deposited material may be given acoat of etch-resisting material such as printer's ink and the backcovered with shellac and the stripped sheet then immersed in an etchingbath which will cut through the thin portions which are formed over theprotuberances.

In certain instances it may be desirable to spread over the wax a verythin coat of graphite of very low conductivity.

It will be apparent that a procedure such as.

described will result in the provision of a highly satisfactory screenfor many purposes, and, when the protuberances are properly spaced andof proper height, will result in the production of a screen embodying,the feature of the invention wherein the land of the screen is deeperthan the distance between adjacent holes.

Materials which are highly desirable for use in providing theprotuberances in matrices are synthetic rubber compositions, such, forinstance, as those synthesized from acetylene. example of such acomposition is the material found on the market under the trade nameDuprene". Such material is in general resistant to etching chemicals andhas sumcient cohesion to insure against breaking when anelectro-deposited screen is stripped oil.

In certain instances it is desirable to provide a particularly thickscreenfiand for such use a material such as indicated above may beeffectively used.

Deep matrices adapted for formation of thick screens may be formed bythe procedure exemplifled below.

A thin sheet of electrolytic copper, preferably electro-deposited in athin sheet which may be less than 0.0030 of an inch thick and which ispreferably less than 0.0015 of an inch thick, is attached, as byadhesive tape, at the edges to a flat plate of suitable material such asplate-glass. In certain instances it may be advisable to reduce furtherthe thickness of the original electro-deposited sheet. This may beaccomplished in any convenient fashion, as by grinding orelectro-corrosion. It is preferably carried out by etching which givesan especially even surface. Splash and spray etching are particularlyeffective. The screen is then cleaned and treated for printing, as bybeing coated with a sensitized glue solution and dried as describedabove. Thereupon, it is subjected to a suitable printing process whichmay be similar to that above described in connection with Fig. 1 andremoved from the glass plate. The back of the plate (the face oppositeto the face treated with glue) is thereupon given a thick coat ofshellac which in this instance is allowed to dry only partially. Thesheet is next spread upon a glass plate 20 again with the tacky film 12aof shellac against the plate, and immersed in an etching solution (e.g.. ferric chloride) until the portions from which the unexposed gluehas been washed, etch completely through the sheet, as shown in Fig. 11.Alcohol, carried in this case, in the partiallydry shellac, acts toretard the etching of those holes which etch through first, and toprevent the usual tendency for certain of the holes to be etchedradially outward from their respective axes to a greater extent than theothers. The evenness of the alcohol layer appears to be a contributingfactor in obtaining a uniform etch. A screen, as formed; above, isexemplified in Fig. 12. A screen formed in this manner is desirable fora number of uses without further treatment. In order to form a matrix,or a thicker screen, however, the screen shown in Fig. 12, after beingthoroughly cleaned, is electroplated on all sides with copper to buildup a screen such as shown in Fig. 13. It is then rolled with anacid-proof ink 2|, stencilling paste or other etch-resisting material,on bothfaces and again etched to reduce the width of the land, providinga screen as shown in Fig. 14. The foregoing plating and etchingprocedure is repeated until a thick screen without an undue amount ofland is provided. In certain cases it may not be necessary to etch outthe perforations after additional metal has been deposited upon thescreen, as it has been found that under certain conditions the metal isdeposited principally upon the faces of the sheet with little or nodeposit on the surfaces of the perforations. This screen likewise isdesirable itself for various uses.

.usedasanintermediateproduct surface. The screen shows in Fig.1

in A nlitable cover,

tion of a deep matrix. such, forinstance,a.sa eceolpaperflmadetacky withglue, is secured to the side of the screen where the holes are smallest.and the holes on the other side are filled with synthetic rubberllkematerial or other .desirable non-oonductini material a. The syntheticrubber-like material may be cut with naphtha and poured in. The surfaceof the sheet is immediately dusted over with copper, sine or othersuitable conducting material 21 in granular form. The appearance of thematrix at this stale isilhmtrat edin Fig. 15. After the naphtha hasdried out, the glued paper is removed and the screen subjected to arelatively high temperature, e. g., 250' R, for about three hours tovulcanise the rubber compound. After vulcanization the side of thescreen which carried the glued paper is protected and the other sidesmoothed off to the original metal. The protection may be accomplishedby providing a coat 2 of shellac, and the removal may be accomplished byrubbing with fine sandpaper. Thereupon metal, e. g. copper, iselectro-deposited on the granular material and on the cleaned metal (seeFig. 16) to provide a sheet 20. The granular material serves to securethe deposited and the non-conducting material firmly together. Theshellac is then washed off the original sheet and the face of thedeposited metal protected, as by a coat of shellac. The sheet is thenetched to cut away the original metallic material between the rubberprotuberances to provide a finished matrix as shown in Hg. 11. Byprocedures such as described above, screens of particular thickness maybe readily formed on this matrix.

Under certain circumstances it is desirable to utilize the screen shownin rigs. 12 or 14 as a master screen to produce a matrix for the screensby a method which is a modification of the above method. A suitablecover such as apiece of paper 22, made tacky with glue, is secured tothe side of the screen when the holes are smallest and the holes in thescreen'are filled from the side on which they are larger with asynthetic rubber-like material or other desirable non-conductingmaterial 23. This material is also spread entirely over the faceopposite the paper If. as, shown in Fig. 18; The paper I! is then takenoff and the metal I. removed in any suitable fashion as byetching, so asto leave a matrix 21 having a back It and protuberances It all ofnon-conducting material as shown in Fig. 19.

The troughs between the protuberances are caused to become conductingsurfaces. This may be accomplished by dusting with a metallic powder 80,which latter may better adhere to the surface by first applying a stickywax solution II to the surface (see Fig. 20). The metallic powder mayberemoved from the tops of the protuberances by rolling up" the matrixwith a greasy ink. The powder remaining is connected to one electrode inan electrolyte and the device is then ready to act as a matrix for thedeposit thereon of a screen. When a screen 82 has been deposited (seeFig. 21) on the matrix to the desired dept-h it may be removed bystripping it (see Fig. 22) from the matrix.

Thetroughsmayalsoberendsredconducting by any other convenient method,for example, by precipitating a metal such as silver on the surface ofthe non-conducting material and rolling thetopsoftheprotuberanceswithagreasyink.

The eiectrodeposit of the screen I! in Fig. 21 is facilitated by slowlyimmersing the matrix into the electrolyte, the portion of the matrixfarthest removed from the attached electrode going into the bath first.The rate of immersion is sufiiciently slow to allow a relatively smallarea to have atdeast a very thin uniform layer deposited thereon beforethe adjacent area is immersed. In order that the entire matrix may becovered with a deposit of uniform thickness the end of the matrix whichis immersed first may be removed from the electrolyte first, the rate ofpassage into and. out of the electrolyte being constant.

It should be noted that for purposes of clarity the dimensions in thedrawings are exaggerated and particularly the dimension which gives theheight of the protuberances. Screens made according to the methodsdescribed herein sometimes have 250,000 perforations per square inch.

If the screen builds up in little collars or cones about theprotuberances, these collars may be removed from the screen by grindingand etching.

The inking step may be omitted before the electro-deposition. Instead,after deposition has been begun, the deposited metal 32 may be rolled aup" with a greasy ink 33 which will adhere only to the tops, or tops andpart way down the sides, of the metal protuberances. The deposit is thencontinued whereby only the troughs become more deeply inlaid with metal.After stripping the screen from the matrix and washing off the ink, arelatively slight etching will remove the relatively small amount ofmetal first deposited on the tops of the matrix protuberances and willleave the desired screen with perforations extending therethrough.

In case the last-mentioned etching is carried out over a predeterminedlydesigned portion 34 of the screen, the final screen forms a stencil ofthe type used in silk screen" printing with perforations 38 from oneface of the screen to the other only within the boundaries-of theportion 34, as shown in Figs. 24 and 25. Such a screen made from a deepmatrix like that shown in Fig. 19 from the process described inconnection with n Fig. 14 is particularly strong and effective althoughany of the methods described above for securing the vertical-sideddepressions on one side of the screen may be utilized.

Since certain changes in carrying out the above process, and certainmodifications in the article which embody the invention may be madewithout departing from its scope, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be Q interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereinde- .5 scribed, and all statements of the scope of the invention which,as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secureby Letters Patent, is: 7

l. The process of making a screen, comprising electro-depositing a sheetof material in a layer on a matrix which has protuberances to a depthwhereby said protuberances are at leastsubstantiallycoveredbythedepositremovingtheu amass-r deposited materialfrom said matrix as a sheet having depressions on one face thereofcorresponding to said protuberances and removing a portion of the otherface of said sheet opposite to the face having. said depressions toadepth such that certain of said depressions are reached.

2. The process of making a screen, comprising forming a master screen,filling the interstices of said master screen with non-conductingmaterial, providing-a back common to the material in said interstices,removing said master screen and applying a conducting surface to saidnonconducting material, electro-depositing a sheet of metal in a layeron said conducting surface, removing said metal as a sheet havingdepressions on one face thereof corresponding to the shape of saidnon-conducting material and removing a portion of the other face of saidsheet opposite to the facehaving said depressions to a depth such thatcertain of said depressions are reached.

3. A matrix for the electro-depcsition of a metallic screen of the typedescribed comprising a plurality of spaced bodies ofnon-conductingmaterial supported by a backing sheet of metal, the saidspaced bodies being protuberant 'and of substantial height and united tosaid backing sheet by electro-deposition.

4. The process of producing an electrolytically deposited screen, theland thickness of which bears a ratio to the land width substantiallygreater than that which would result from electrolytic deposit merely onan unconfined conducting area conforming to the pattern of the screen tobe produced, which said process comprises providing a matrix theexposure surface of which includes a conducting area and nonconductingbodies projecting therefrom, said nonconducting bodies being composed ofmaterial of rubber-like resilience and being of substantial height forlimiting lateral spread of an electrolytic deposit on the conductingarea, then laying on said conducting surface an electrolytic deposit ofthe desired thickness, and then stripping the deposit from the matrix.

5. Process of producing an electrolytically deposited screen, the landthickness of which bears a ratio to the land width substantially greaterthan that which would result from electrolytic deposition merely on anunconfined conducting I area conforming to the pattern of the screen tobe produced, which said process comprises providing a matrix theexposure surface of which comprises a conducting area andnon-conducting.

bodies projecting therefrom for limiting lateral spread of anelectrolytic deposit on the conducting area, said non-conducting bodiesbeing of substantial height and diminishing in cross-section area as theheight increases, then laying on said conducting area an electrolyticdeposit of the desired thickness, and then stripping the deposit fromthe matrix.

6. The process of producing an electrolytically deposited screen of apredetermined pattern,

* minimum and maximum land widths and hole dimensions, the landthickness of which bears a predetermined ratio to the said minimum landwidth substantially greater than that which would result fromelectrolytic deposition merely on an unconfined conducting areaconforming to the said predetermined screen pattern and of the saidpredetermined minimum land width, which said process comprises providinga matrix the exposure surface of which comprises a conducting area of apattern conforming to the predetermined screen pattern and of theminimum width dimension ofthe lands of thescreen to be produced, andalso comprises means for limiting lateral spread of an electrolyticdeposit on the said conducting area comprising cores of nonconductingmaterial constituting non-conducting areas of said exposure surface andprojecting to a height above said conducting areas at leastsubstantially equal to that of the land thickness of the screen to bedeposited and of a section progressively diminishing as the heightincreases, then laying on said conducting surface an electrolyticdeposit of the said land thickness, and then stripping the deposit fromthe matrix.

7. .A matrix of the type described, comprising a plurality of spacedbodies of material presenting a surface inactive to electrolyticdeposition and supported by and aiilxed to a backing sheet presenting aconductive surface, the said spaced bodies being protuberant andprojected from said conductive surface to a substantial height anddiminishing in cross-section area as the height increases.

8. A process of screen formation, which comprises imposing anetch-resistant material upon a metal sheet in a design, etching saidsheet away completely through between the faces thereof where notcovered by said design, removing said material, inserting materialpresenting a surface inactive to electrolytic deposition in the spaceswhich have been etched out, coating one face of said sheet withconducting material, electro-depositing a reinforcing metal backing onthe said face, removing the metal on the opposite face of said sheetuniformly-to a depth that permits the material in said spaces toproject, applying to the said opposite face a separating film which willnot prevent electro-deposition, building up a deposit on said oppositeface by electro-deposition on those portions of the same not covered bysaid material in said spaces and stripping said deposit away as ascreen.

9. In a process of screen formation, the steps which comprise applyingan etch-resistant material to a sheet in the form of a design to a sheetof conducting material, etching away said sheet completely throughbetween the faces thereof where not covered by said design wherebyperforations are formed, removing said etch-resistant material, fillingsaid perforations with material presenting a surface inactive toelectrolytic deposition, reinforcing said sheet by applying thereto abacking of conducting material and removing at least a portion of themetal from the opposite side of the sheet to a uniform depth over thesurface thereof and to a depth sufficient to allow the material in saidperforations to project beyond the surface of said sheet.

10. A matrix of the type described, comprising a plurality of spacedbodies of material having a rubber-like resilience and presenting asurface inactive to electrolytic deposition supported by and aiiixed toa backing sheet of metal, the said spaced bodies being protuberant andof substantial height.

11. A matrix for the electro-deposition of a foraminous sheet,comprising a plurality of bodies of material presenting a surfaceinactive to electrolytic deposition and supported by a backing sheetpresenting a conducting surface, the said spaced bodies being arrangedin predetermined positional relationship and being protuberant andprojecting from said conducting surcross-sectional areas as the heightincreases.

ll."lheproessotprodueingamatrlxtorthe productionoisnslectrodepositedscrmstencil,andthelike.whichcomprisesiillingwithmaterialpresentingasurisceinactivetoelectrolytic depositiontheperiontionsotioramincussheetoiiirstmcntionedmaterialprotuherantandoisuhstantialheight. I

13.!heprocemotpmdudngamatrixiorthe production olanelectro-depositedscreen. stencil andthelike.whichcomprisesflllingthe perforations ortoraminom sheet of electrically conductive material with materialpresenting a surtaoe inactivetcelectrolytic deposition and apnly lanadherentcoatingtoonesurlaceolssid sheet andtotheexposedareasoithematerialinsaidper- Iorations.

14.!heprocess ofproducingamatrlx iorthe production of anelectro-deposited screen, stencilandthelike,whlchcomprlsesiillingtheper-Iorstions of ioraminom metal sheet withmaterialpresentingasurtaocinactivs'toelectrolytic arm toone o!deposition mum an adherent coating surface of said sheet and to theexposed the material in said perforations and removingtromtheexposedmetallicareasoitheotheriscotsaidsheetenoughmetaltocamethematcrial in said periorations to projectbeyond said metallic areas. 4

15. The process of producing a matrix (or the production oi anelectro-deposited screen. stencil and the like, which comprises fillingthe perforations of ioraminous sheet .0! electrically conductivematerial with material presenting a surface inactive to electrolyticdeposition applying to one surface of said sheet and to the exposedareas oi material in said perlorations an adherent coating entirelycovering the same, and removing to a uniform depth from the electricallyconductive areas 0! the other face of said sheet enough material tocause the materialin said periorations to project beyond said areas ofelectrim cally conductive material.

EDWARD OMAR NORRIS.

